I'm working on a tool made for professionals to calculate advice for their customers. The user is following predefined steps. The steps are represented as tabs (with arrows) in the interface.
The user will most of the time follow these steps.
However, it is possible that the user will change a bit of information in an earlier step.
in step 4 the user makes a selection, based on the result of a calculation.
in step 3 a calculation is presented where one of the amounts used, appear to be incorrect
and in step 2 some amounts are entered that will be used for the calculation.
The user will go back from step 4 to step 2, change the value. When that value has changed, the calculation in step 3 made has become invalid. And all the choices made in step 4, based on the former calculation, has also become invalid.
How should I deal with this situation?